The reciting of Shema is the Jewish declaration of faith, and thereby, in a sense, it encompasses the entire Torah. Reciting it morning and evening is an act of engaging in Torah study day and night, and vigilance in its recitation attests to the fact that one is following the path of uprightness.

This reciting of Shema, if a person recites it morning and evening, the Holy One, blessed be He, ascribes to him as though he were immersing himself in Torah study day and night.

The Sages taught in the name of Rabbi Meir: Anyone who resides permanently in the Land of Israel; speaks in the sacred tongue, Hebrew; eats produce in ritual purity; and recites Shema morning and evening is informed that he has a place in the World to Come. (Midrash Tehillim 1; Jerusalem Talmud, Shekalim 3:3)